Practical midwifery; handbook of treatment . pass of a single forceps, by adopting one of those models whichare furnished with accessory axis-traction appliances; and whichare so little modified that the blades when divested of their axis-traction rods, aie still suitable for low operations. Axis-traction Forceps.—It has long been known that whenthe forceps is applied to the head at the superior strait, and trac-tion is made upon the handles, the line of effort is such that. OBSTETRIC SURGERY. 151 under the most fa vox-able circumstances, a large portion of theforce expended is wasted in compr
Practical midwifery; handbook of treatment . pass of a single forceps, by adopting one of those models whichare furnished with accessory axis-traction appliances; and whichare so little modified that the blades when divested of their axis-traction rods, aie still suitable for low operations. Axis-traction Forceps.—It has long been known that whenthe forceps is applied to the head at the superior strait, and trac-tion is made upon the handles, the line of effort is such that. OBSTETRIC SURGERY. 151 under the most fa vox-able circumstances, a large portion of theforce expended is wasted in compression of the head against thetissues of the anterior pelvic wall (Fig. 23). From an early datemany efforts have been made to altef the line of traction, eithei Fig. 23.—Axis Traction. by bending the handles backward, or by attaching rigid tractionarms of similar effect; but the exact line in which traction shouldbe applied varies so much with the varying presentations andpositions of the head, and with the variations in the form of in-. FiG. 24.—Tarniers Axis-traction Forceps. dividual pelves, that the line of traction furnished by any rigidinstrument is likely to be little less erroneous in a given case thanis that of the simple instrument; and the advantages of theseforceps proved to be so slight that none of them ever attainedany wide popularity. It remained for Tarnier to invent the firstreally useful axis-traction instrument (Fig. 24), by adapting to 152 PRACTICAL MIDWIFERY. the ordinary forceps a pair of curved rods, attached to the bladesat a point close to their grasp upon the head, by. a freely mova-ble joint. With this appliance, if traction is made in an even ap-proximatelj correct direction, the head moves automatically inthe direction of least resistance under the influence of the me-chanical forces involved; and the delivery is consequentlyeffected by the expenditure of the least possible degree of force,and it is a noteworthy fact that all the successful i
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectmidwifery, bookyear18
